I think that thoughts and experiences like these arise because there is massive shortage of 'saviour' archetypes in society, relative to the number that we need to get rid of all the shit flying around. On psychedelic drugs it is possible to become aware of what is possible for your self to become and to achieve. Because they can give us a sense of being connected to the divine ground (or whatever you want to call it) and also a sense of purpose, the idea of self moves from mundane through heroic to messianic.
Our society sneers at ideas of universal love, interconnectedness and indeed at finding nobilty and honour in humans outside the cinema. Since the world seen through psychedelics often makes these concepts apparent, obvious even, a stark contrast is immediately drawn with the straight world and some form of enlightenment is felt. The Jesus archetype is unique since in mainstream christian 'theology' the entire weight of mankind's sins can be borne on his shoulders. This is not true of, say, Buddha.
I suppose you could say that perhaps under the influence of psychedelics we can become more aware of our (effectively) infinite potential and genuine ability to affect great change in the world around us i.e bear the weight of the world on our own shoulders. Or it could just be total delusion...